Energy Blog: SMRs Are Promising, but Disposal Issues Remain

There may be some momentum beginning to build in the deployment of small, modular nuclear reactors in the U.S. and globally. The push for renewable sources of clean energy continues, and nuclear’s ability to produce constant, baseload power without emitting greenhouse gasses has allowed SMRs to remain an option despite policies that have seen earlier nuclear plants retire.

SMRs are considered a less expensive and swifter option to create and develop nuclear energy capacity. A handful of firms have been developing the technology, including Rolls Royce, which last year announced the formation of Rolls-Royce Small Modular Reactor company. The firm projected each SMR, capable of generating 470 MW, could roughly cost $2.7 billion to build. That’s far less than traditional nukes, which have run upward of $20 billion or so.

There are 440 nuclear reactors now operating globally, generating about 10 percent of the world’s electricity. The U.S. now has 93 nuclear generators providing about one-fifth of the country’s power supply.

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Oregon-based NuScale Power Corp.’s basic nuclear module would generate 77 MW of power, and could be packaged in configuration of four, six and 12 modules. It received Standard Design Approval from the U.S. Nuclear Commission in 2020, still the only firm to land the designation.

NuScale last year also won a $1.35-billion award from the Department of Energy to fund the Carbon Free Power Project, potentially a 720-MW plant the Utah Associated Municipal Power Systems is developing at the Idaho National Laboratory. Earlier this year, the firm and Romania’s state nuclear power corporaton signed a memorandum of understanding for initial studies, permitting and licensing for an SMR to be built in Doicesti, Romania.

Last year, DOE also selected TerraPower and GE Hitachi Nuclear Energy’s Natrium, and X-Energy’s Xe-100 designs for initial funding under the Advanced Reactor Demonstration program.

Patrick Moore, former director of Greenpeace, again reiterated his support for nuclear energy in a recent television interview, shortly after the European Parliament supported the addition of nuclear and natural gas to the EU’s grouping of environmentally sustainable, green technologies.

“Nuclear energy is the safest of all the electricity technologies we have,” he said. “Nuclear is the one technology that can actually replace a lot of the fossil fuels. Because fossil fuels are precious, and we should save them for things that can only be done with fossil fuels, like flying airplanes, large trucks, and big farm equipment.”

Greenpeace does not agree with Moore, and will petition the EU to backtrack on the issue. And there is still another hurdle to overcome: how and where to dispose of spent fuel.

A new report out of Stanford University and the University of British Columbia claims SMRs could produce up to 30 times more radioactive waste than existing nuclear plants.

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“Our results show that most small modular reactor designs will actually increase the volume of nuclear waste in need of management and disposal, by factors of 2 to 30 for the reactors in our case study,” said Lindsay Krall, the study’s lead author, in a release announcing the study results. “These findings stand in sharp contrast to the cost and waste reduction benefits that advocates have claimed for advanced nuclear technologies.”

The study looked at three types of SMRs being developed by Toshiba, NuScale, and Terrestrial Energy. Each has a different design. Results of the case studies were corroborated by theoretical calculations and a broader design survey, according to the researchers.

“The analysis was difficult because none of these reactors are in operation yet,” said study co-author Rodney Eweing, the Frank Stanton Professor in Nuclear Security at Stanford and co-director of Stanford’s Center for International Security and Cooperation. “Also, the designs of some of the reactors are proprietary, adding additional hurdles to the research.”

The study found that the smaller SMR design will experience more neutron leakage than a conventional reactor, affecting the amount and composition of waste streams. Neutron leakage is a term to describe neutrons escaping from the core, striking surrounding structural materials that then become radioactive.

“The more neutrons that are leaked, the greater amount of radioactivity created by the activation process of neutrons,” Ewing said. “We found that small modular reactors will generate at least nine times more neutron-activated steel than conventional power plants. These radioactive materials have to be carefully managed prior to disposal, which will be expensive.”

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Nuclear waste disposal has been contentious for decades. In 1987, Congress designated development of a permanent disposal site at Yucca Mountain in Nevada. The state successfully blocked operation in 2004, citing safety concerns, and the Obama administration dropped it altoghether. Most high-level waste from nuclear power plants consists of spent fuel rods, now stored under water in pools on site.

The study’s authors also claim spent fuel from SMRs will be discharged in greater volumes per unit energy extracted, and “can be far more complex” than spent fuel from existing plants.

“Small modular reactor designs call for chemically exotic fuels and coolants that can produce difficult-to-manage wastes for disposal,” said Allison Macfarlane, a co-author and professor and director of the School for Public Policy and Global Affairs at the University of British Columbia. “The takeaway message for industry and investors is that the back end of the fuel cycle may include hidden costs that must be addressed.”

John Kosowatz is senior editor.